The Inversion of Seepage Parameters by Tidal and Barometric Response Methods: A Case Study of Shizhu Well with the Thick Aquifer Mixed with Mudstones

Permeability affects the process of underground seepage, which is essential in the underground engineering field, and has significant implications for resource exploitation and the surrounding ecological environment. Tidal response analyses of the groundwater level with the leaky models can calculate permeability and judge layer leakage. However, model limitations, data quality, solution methods, etc. will affect the final calculation results and the judgment of layer leakage. In this study, the well analyzed is in the Chongqing province, and is with a relatively thick aquifer (mixed with mudstones) compared to the thickness of the aquitard. Therefore, the method of the tidal response leaky model based on the assumption of a thin aquifer could not be precisely applicable, but still could be used to do a rough estimation. Besides, we improved the barometric response leaky model, and verified the tidal response calculation results in Shizhu well, which show the result of unity. Both of the results show that during the ten years from 2009 to 2019, obvious vertical leakage occurred in the aquitard of the shallow (about 120 m deep) strata in the Shizhu area. Which calls for cautious usage of shallow groundwater for the perhaps existing vertical leakage of the surface agricultural pollutant, bacteria and pesticides into the groundwater in the Shizhu area in Chongqing Province.